Multiprobes with thermal diffusion flow monitor

• US 5,207,227 A
• Filed: 05/10/1991
• Issued: 05/04/1993
• Est. Priority Date: 03/02/1990
• Status: Expired due to Fees

• Current Assignee: Alexandros D. Powers
• Original Assignee: Alexandros D. Powers
• Inventors: Powers, Alexandros D.
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): Pfaffle, Krista M.
• Application Number:
  US07/701,353
• Time in Patent Office: 725 Days
• Field of Search: 128/670, 128/673, 128/675, 128/692, 128/691, 128/736, 73/202.5, 73/204.16, 73/204.17, 73/204.26, 73/204.27
• US Class Current: 600/504
• CPC Class Codes: A61B 5/028 by thermo-dilution
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: G01F 1/684 Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
• CPC Class Codes: G01F 1/688 using a particular type of heating, cooling or sensing element G01F1/6847 takes precedence
• CPC Class Codes: G01L 19/0092 Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26

Abstract

A single probe with thermal diffusion flow monitor (hereinafter known as "SPTDFM") that has improved reliability, smaller overall size, simpler method of sensor positioning, better compatibility and capability to monitor blood flow, pressure and other critical physiological parameters is provided. The SPTDFM is formed by the combination of a thermal diffusion flow monitor, a pressure monitor, a multiple parameter monitor and a support structure.

Claims

1. A single probe system useful for monitoring blood flow in a tissue comprises:

a support structure having a first side surface and a second side surface opposite to said first side surface,

an anterior and a posterior surface connected to said first and second side surfaces;

thermal diffusion means to measure blood flow housed in said support structure near said first side surface,

said thermal diffusion means further comprises a conical hot film probe with a sensor tip adapted to contact the tissue, wherein said sensor tip comprises a thin metal layer;

a backing material onto which said thin metal layer is deposited;

a protective coating deposited over said thin metal layer;

control means to heat said sensor tip as a heat source while simultaneously measuring a temperature correlating to the blood flow in the tissue;

pressure monitor means housed in said support structure near said anterior surface and adjacent to said thermal diffusion means to monitor pressure in the tissue; and

multiple parameter means housed in said support structure near said second surface and adjacent to said pressure monitor means to monitor oxygen content, temperature and potential of the tissue.

2. The single probe system of claim 1, wherein said pressure monitor means further comprises a pressure transducer having a movable diaphragm and strain gauge that is displaced in accordance with the pressure exerted by the tissue.

3. The single probe system of claim 2, wherein said pressure monitor means further comprises a pneumatic circuit connected to said movable diaphragm and strain gauge to balance the displacement of said diaphragm and strain gauge by the pressure exerted by the tissue.

4. The single probe system of claim 2, wherein said pressure monitor means further comprises a fiber optic photodetector system connected to said movable diaphragm and strain gauge to measure pressure exerted by the tissue;

said photodetector system comprises;

a photodetector,

a light source,

a fiber optic cable to carry a light from said source onto a reflective surface connected to said movable diaphragm at a first position;

whereby a first reflected light is reflected from said reflective surface onto said photodetector; and

measuring means to measure a change of light intensity at said photodetector when a second reflected light is reflected from said reflective surface when said movable diaphragm is at a second position in accordance with the pressure exerted by the tissue.

5. The single probe system of claim 1, wherein said support structure further comprises a silicone based catheter.

6. The single probe system of claim 5, wherein said catheter further comprises a side port for advancing said thermal diffusion means into the tissue.

7. The single probe system of claim 1, further comprises an introducer surrounding said support structure to reduce inaccuracy in blood flow measurements.

8. A method of monitoring blood flow in a tissue comprising the steps of:

cutting a skin incision of about 1 cm in a protective covering of the tissue;

inserting the single probe system of claim 1 into the tissue;

heating said sensor tip as a heat source while simultaneously measuring a temperature of the tissue and correlating said temperature to blood flow in the tissue.

9. A single probe system useful for monitoring blood flow in a tissue comprises:

a support structure having a first side surface and a second side surface opposite to said first side surface,

an anterior and a posterior surface connected to said first and second side surfaces;

thermal diffusion means to measure blood flow housed in said support structure near said first side surface,

said thermal diffusion means further comprises a conical hot film probe with a plurality of sensor tips adapted to contact the tissue, wherein each sensor tip comprises a thin metal layer;

a backing material onto which said thin metal layer is deposited;

a protective coating deposited over said thin metal layer;

control means to heat a first sensor tip of said plurality of sensor tips as a heat source while simultaneously measuring temperature drops of sensor tips other than said first sensor tip of said plurality of sensor tips at a distance of d₁ or multiples thereof from said first sensor tip, and correlating said temperature drops to the blood flow in the tissue;

pressure monitor means housed in said support structure near said anterior surface and adjacent to said thermal diffusion means to monitor pressure in the tissue; and

multiple parameter means housed in said support structure near said second surface and adjacent to said pressure monitor means to monitor oxygen content, temperature and potential of the tissue.

10. The single probe system of claim 9, wherein said pressure monitor means further comprises a pressure transducer having a movable diaphragm and strain gauge that is displaced in accordance with the pressure exerted by the tissue.

11. The single probe system of claim 10, wherein said pressure monitor means further comprises a pneumatic circuit connected to said movable diaphragm and strain gauge to balance the displacement of said diaphragm and strain gauge by the pressure exerted by the tissue.

12. The single probe system of claim 10, wherein said pressure monitor means further comprises a fiber optic photodetector system connected to said movable diaphragm and strain gauge to measure pressure exerted by the tissue;

said photodetector system comprises;

a photodetector,

a light source,

a fiber optic cable to carry a light from said source onto a reflective surface connected to said movable diaphragm at a first position;

whereby a first reflected light is reflected from said reflective surface onto said photodetector; and

measuring means to measure a change of light intensity at said photodetector when a second reflected light is reflected from said reflective surface when said movable diaphragm is at a second position in accordance with the pressure exerted by the tissue.

13. The single probe system of claim 9, wherein said support structure further comprises a silicone based catheter.

14. The single probe system of claim 13, wherein said catheter further comprises a side port for advancing said thermal diffusion means into the tissue.

15. The single probe system of claim 9, further comprises an introducer surrounding said support structure to reduce inaccuracy in blood flow measurements.

16. A method of monitoring blood flow in a tissue comprising the steps of:

cutting a skin incision of about 1 cm in a protective covering of the tissue;

inserting the single probe system of claim 9 into the tissue; and

heating said sensor tip of said plurality of sensor tips as a heat source while simultaneously measuring temperature drops of sensor tips other than said first sensor tip of said plurality of sensor tips at a distance of d₁ or multiples thereof from said sensor tip and correlating said temperature drops to the blood flow in the tissue.

17. A single probe system useful for monitoring blood flow in a tissue comprises:

a support structure having a first side surface and a second side surface opposite to said first side surface,

an anterior and a posterior surface connected to said first and second side surfaces;

thermal diffusion means to measure blood flow housed in said support structure near said first side surface,

said thermal diffusion means further comprises a conical hot film probe with a plurality of sensor tips adapted to contact the tissue, wherein each sensor tip comprises a thin metal layer;

a backing material onto which said thin metal layer is deposited;

a protective coating deposited over said thin metal layer;

control means to heat at least two sensor tips of said plurality of sensor tips as heat sources while simultaneously measuring temperature drops of sensor tips other than said first two sensor tips of said plurality of sensor tips at a distance of d₂ or multiples thereof from one of said at least two sensor tips, and correlating said temperatures to the blood flow in the tissue;

pressure monitor means housed in said support structure near said anterior surface and adjacent to said thermal diffusion means to monitor pressure in the tissue; and

multiple parameter means housed in said support structure near said second surface and adjacent to said pressure monitor means to monitor oxygen content, temperature and potential of the tissue.

18. The single probe system of claim 17, wherein said pressure monitor means further comprises a pressure transducer having a movable diaphragm and strain gauge that is displaced in accordance with the pressure exerted by the tissue.

19. The single probe system of claim 18, wherein said pressure monitor means further comprises a pneumatic circuit connected to said movable diaphragm and strain gauge to balance the displacement of said diaphragm and strain gauge by the pressure exerted by the tissue.

20. The single probe system of claim 19, wherein said support structure further comprises a silicone based catheter.

21. The single probe system of claim 20, wherein said catheter further comprises a side port for advancing said thermal diffusion means into the tissue.

22. The single probe system of claim 18, wherein said pressure monitor means further comprises a fiber optic photodetector system connected to said movable diaphragm and strain gauge to measure pressure exerted by the tissue;

said photodetector system comprises;

a photodetector,

a light source,

a fiber optic cable to carry a light from said source onto a reflective surface connected to said movable diaphragm at a first position;

whereby a first reflected light is reflected from said reflective surface onto said photodetector; and

measuring means to measure a change of light intensity at said photodetector when a second reflected light is reflected from said reflective surface when said movable diaphragm is at a second position in accordance with the pressure exerted by the tissue.

23. The single probe system of claim 17, further comprises an introducer surrounding said support structure to reduce inaccuracy in blood flow measurements.

24. A method of monitoring blood flow in a tissue comprising the steps of:

cutting a skin incision of about 1 cm in a protective covering of the tissue;

inserting the single probe system of claim 17 into the tissue; and

heating at least two sensor tips of said plurality of sensor tips as a heat source while simultaneously measuring temperature drops of sensor tips other than said at least two sensor tips of said plurality of sensor tips at a distance of d₂ or multiples thereof from one of said at least two sensor tips;

, and correlating said temperature drops to the blood flow in the tissue;

25. A thermal diffusion means useful for monitoring blood flow in a tissue comprises:

a conical hot film probe with a plurality of sensor tips adapted to contact the tissue, wherein each sensor tip comprises a thin metal layer;

a backing material onto which said thin metal layer is deposited;

a protective coating deposited over said thin metal layer; and

control means to heat a first sensor tip of said plurality of sensor tips as a heat source while simultaneously measuring temperature drops of sensor tips other than said first sensor tip of said plurality of sensor tips at a distance of d₁ or multiples thereof from said first sensor tip, and correlating said temperature drops to the blood flow in the tissue.

26. A thermal diffusion means useful for monitoring blood flow in a tissue comprising:

a conical hot film probe with a plurality of sensor tips adapted to contact the tissue, wherein each sensor tip comprises a thin metal layer;

a backing material onto which said thin metal layer is deposited;

a protective coating deposited over said thin metal layer; and

control means to heat at least two sensor tips of said plurality of sensor tips as heat sources while simultaneously measuring temperature drops of sensor tips other than said at least two sensor tips of said plurality of sensor tips at a distance of d₂ or multiples thereof from one of said at least two sensor tips, and correlating said temperature drops to the blood flow in the tissue.